Imido-substituted organopolysiloxane compositions

ABSTRACT

CURABLE ORGANOPOLYSILOXANE COMPOSITIONS ARE PROVIDED AND A METHOD FOR MAKING THEM, COMPRISING ORGANOPOLYSILOXANE HAVING ONE OR MORE ALIPHATICALLY UNSATURATED IMIDO ORGANO RADICALS ATTACHED TO SILICON THROUGH A CARBON-SILICON BOND. THE CURABLE ORGANOPOLYSILOXANE COMPOSITIONS CAN BE IN THE FORM OF BLENDS OF SUCH IMIDO-SUBSTITUTED ORGANOPOLYSILOXANE IN COMBINATION WITH AT LEAST ONE OLEFINICALLY UNSATURATED MONOMER, SUCH AS N-PHENYLMALEIMIDE, BISMALEMIDE, STYRENE, ETC., OR AT LEAST ONE POLYMER, SUCH AS POLYCARBONATE, POLYVINYLCHLORIDE, ETC., OR MIXTURES THEREOF.

United States Patent 3,558,741 lMIDO-SUBSTITUTED ORGANOPOLYSILOXANECOMPOSITIONS Fred F. Holub and Milton L. Evans, Schenectady, N.assignors to General Electric Company, a corporation of New York NoDrawing. Filed May 5, 1969, Ser. No. 821,966 Int. Cl. C08f 35/02; C08g31/24, 47/10 US. Cl. 260-827 ABSTRACT OF THE DISCLOSURE 'CurabIeorganopolysiloxane compositions are provided and a method for makingthem, comprising organopolysiloxane having one or more aliphaticallyunsaturated imido organo radicals attached to silicon through acarbon-silicon bond. The curable organopolysiloxane compositions can bein the form of blends of such imido-substituted organopolysiloxane incombination with at least one olefinically unsaturated monomer, such asN-phenylmaleimide, bismaleimide, styrene, etc., or at least one polymer,such as polycarbonate, polyvinylchloride, etc., or mixtures thereof.

The present invention relates to curable compositions comprisingorganopolysiloxane having chemically-combined aliphatically unsaturatedimido radicals and methods for making such materials.

The curable compositions of the present invention compriseorganopolysiloxane having attached to silicon by carbon-silicon bonds atleast one chemically-combined imido organo radical of the formula WhereR is an aliphatically unsaturated divalent organic radical selected fromthe class consisting of hydrocarbon radicals and halogenated hydrocarbonradicals and R is a divalent organo radical selected from hydrocarbonradicals and halogenated hydrocarbon radicals. Some of the radicalsincluded by R of Formula 1 are, for example,

where X is hydrogen, chloro, or methyl,

CH or E- 9 Claims Patented Jan. 26, 1971 Ice etc. imido-substitutedorganopolysiloxanes included within the scope of the invention have theformula where R" is selected from monovalent hydrocarbon radicals,halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals, Mis a monovalent aliphatically unsaturated organo imido radical includedby 'Formula 1, attached to silicon by a carbon-silicon bond, a has avalue equal to .002 to 3 inclusive, b has a value equal to from 0 to 2.5inclusive, and the sum of a+b has a value equal to from 1 to 3inclusive.

Included by Formula 2, are imido-substituted organopolysiloxanes of theformula,

Where the various terms are as previously defined, and n is an integerequal to from 1 through 1,000, inclusive.

-'Radicals included by R of Formula 1 are, for example, alkyleneradicals such as methylene, ethylene, propylene, butylene, pentylene,etc., arylene radicals such as phenyl ene, tolylene, naphy-thylene, etc.Radicals included by R" of Formula 2 are, for example, aryl radicalssuch as phenyl, tolyl, naphthyl, etc.; halogenated aryl radicals, suchas chlorophenyl, chloronaphthyl, etc.; aliphatic and cyclohalophaticradicals, such as alkyl and haloalkyl radicals, for example, methyl,ethyl, chloroethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, etc.;alkenyl radicals such as vinyl, allyl, etc.; cycloaliphatic radicals,such as cyclopentyl, cyclohexyl, etc.; cyanolakyl radicals, such ascyanoethyl, cyanopropyl, cyanobutyl, etc. Radicals included by R, R andR" of Formulas 1, 2 and 3 can be all the same radical, or a mixture ofany two or more of the aforementioned radicals.

Imido-substituted organopolysiloxanes of the present invention can bemade by efiecting reaction between an aliphatically unsaturatedanhydride of the formula,

and an aminoorganosiloxane of the formula,

5 NEE 2 )1: 1

where R, R, R", a and b are as defined above.

In the course of effecting reaction between the unsaturated anhydride of'Formula 4, and the aminoorganosiloxane of Formula 5, the correspondingamide acid shown by the following formula also can be isolated, iftemperatures up to C. are employed where R, R, 'R", a and b are aspreviously defined. These amide acids can provide for electrocoatingsolutions, employing techniques described in Holub application, Ser. No.548,000, filed May 5, 1966, now U.S. Patent No. 3,507,765 and assignedto the same assignee as the present invention.

Another method of making the imido-substituted organopolysilanes of theinvention is by employing imidosubstituted organosilanes of the formula,

where M and R" are as previously defined, Y is a hydrolyzable radical, cis an integer equal to 1 to 3 inclusive, d is a whole number equal to to2 inclusive, and the sum of c and d is equal to 1 to 3 inclusive. Theimido-substituted organosilanes of Formula 6, and methods for makingthem are shown in our copending application Ser. No. 821,969, filedconcurrently herewith, and assigned to the same assignee of the presentinvention.

There are included by the unsaturated anhydrides of Formula 4, forexample Included by the aminoorgauosiloxanes of Formula 5, are materialshaving at least one chemically-combined aminoorganosiloxy unit of theformula,

where R can be ethylene, propylene, butylene, phenylene, etc. and R" canbe methyl, ethyl, phenyl, cyanoethyl, etc.

4 The aminoorganosiloxane also can include the aforesaidaminoorganosiloxy units chemically-combined with organosiloxy units ofthe formula, such as R"SiO (R) SiO and (R) SiO units, where R" is aspreviously defined. Among the preferred aminoorganosiloxanes of Formula5, there are included disiloxanes of the formula,

where R and M are as previously defined. The imidosubstituteddisiloxanes of Formula 8 can be made by effecting reaction between theaminodisiloxanes of Formula 7 and the unsaturated anhydrides of Formula4.

Another method which can be employed to"'make the imido-substituteddisiloxanes of Formula 8, is by elfecting addition between animido-substituted olefinically unsaturated organic material, and asiloxane hydride as shown as follows:

0 n C II where R' is selected from hydrogen and alkyl radicals such asmethyl, ethyl, etc.

The idimo-substituted disiloxanes of Formula 8 can be equilibrated withorganocyclopolysiloxane of the formula,

sio

where m is an integer equal to 3 to 8, to produce thepolydiorganosiloxanes of Formula 3.

The imido-substituted organopolysiloxanes of Formula 2, also can be madeby hydrolyzing the imido-substituted organosilanes of Formula 6.Depending upon the number or average number of Y radicals attached tosilicon, where Y can be, for example, chloro, ethoxy, diethylaminoxy,etc., the resulting imido-substituted organopolysiloxane can be a fluid,resin or gum. The imido-substituted organosilanes of Formula 6 can becohydrolyzed with organosilanes of the formula,

where R and Y are as previously defined, and e is an integer equal to 1to 3 inclusive.

The imido-substituted organopolysiloxanes of the present invention canbe blended with aliphatically unsaturated organic materials, such asaliphatically unsaturated organic monomers, and organic polymers. Theproportions of the imido-substituted organopolysiloxane and thealiphatically unsaturated organic material, which hereinafter willsignify either the aliphatically unsaturated monomer, organic polymer,or mixture thereof, can vary widely.

Blends of the imido-substituted organopolysiloxanes and theaforementioned aliphatically unsaturated organic material can be madeover wide proportions by weight. Experience has shown that there shouldbe employed at least about 15%, by weight, of the imido-substitutedorganopolysiloxanes to provide for cured products exhibiting suchvaluable characteristics as corona resistance, solvent resistancefiexiblility, etc. Depending upon the Proportion of theimido-substituted organopolysiloxane and the aliphatically unsaturatedmonomer or polymer, the curable blends can provide for laminates,solventless varnishes, molding compounds, coating compositions, etc.Included by the aliphatically unsaturated monomers that can be employedin combination with the imido-substituted organopolysiloxanes are, forexample, styrene, m-phenylene bismaleimide, N-phenylrnaleimide,diallylphthalate, vinyl chloride, isobutylene, butadiene, isoprene,chlorotrifluoroethylene, Z-methylpentene-l; vinyl esters of organiccarboxylic acid, such as vinyl formate, vinyl acetate, acrylonitrile,vinyl methyl ether, vinyl methyl ketone; acrylic esters, such asmethyl-, ethyl-, butyl-, etc., esters of acrylic and methacrylic acids,etc.; divinyl benzene, triallyl citrate, triallyl cyanurate, N-vinylphthalimide, N-allyl phthalimide, N-allyl tetrachlorophthalimide, etc.Among the organic polymer that can be employed in combination with theimido-substituted organopolysiloxane's of the present invention are, forexample, polyvinylchloride, polyethylene, polypropylene, polycarbonates,polysulfones, polystyrene, polyurethane, polyesters,polyphenyleneoxides, acrylonitrile-butadiene-styrene terpolymers,propylene-ethylene copolymers, etc.

The curable organopolysiloxanes of the present inven tion can be curedto the infusible, or elastomeric state with heat, conventional freeradical initiators, irradiation with high energy electrons, X-rays,electromagnetic waves, etc., depending upon the crosslink density of theresulting cured composition. For example, a linear polydiorganosiloxaneincluded by Formula 3 can provide for an elastomer or a thermosetdepending upon the value of n. When n is greater than 5, for example, anelastomer can be made. Cure of the imido-substituted organopolysiloxanesalso can be achieved with room temperature vulcanizing curing catalysts,such as shown by Beers, Pat. 3,382,205, assigned to the same assignee asthe present invention, when utilizing silanol terminated imidesubstituted polydiorganosiloxane, such as polymer consisting essentiallyof chemically combined SiO M units and units. Cure of theimido-substituted polydiorganosiloxane also can be achieved by employingorganosilicon hydrides and platinum catalysts as taught by Chalk, Pat.3,344,111, assigned to the same assignee as the present invention.

When effecting the cure of the curable compositions of the invention byuse of free radical initiators, a temperature of from 50 C. to 300 C.can be employed while 125 C. to 200 C. have sometimes been found to bemore desirable. Acceleration of the cure can be achieved with organicperoxides such as dicumyl peroxide, benzoyl peroxide, tertiary butylperbenzoate, azobis-isobutyronitrile, tertiary-alkyl peroxycarbonate,etc. These can be employed from about 0.01 percent up to about 5percent, by weight, of peroxides, based on the weight of the materialundergoing cure.

In preparing the imido-substituted organopolysiloxanes of Formula 3 bythe anhydride-amine method, reaction can be effected at temperaturesbetween 40 C. to 200 C. Reaction times of as little as two minutes orless to four hours, or more, will depend on such factors as thereactants employed, conditions utilized, presence or absence ofsolvents, dehydrating agents, etc. A suitable organic solvent has inparticular instances been found to facilitate the removal of waterformed during the anhydride-amine condensation which can be azeotropedfrom the mixture. A suitable organic solvent is any solvent inert to thereactants under reaction conditions which facilitate the separation ofwater from the mixture. For example, there are included organicsolvents,

such as N, N-dimethylformamide, toluene, benzene, pyridine, etc.

Equilibration of the imido-substituted disiloxane of Formula 8 andorganocyclopolysiloxane of Formula 9 can be performed at temperaturesbetween 20 C. to 160 C., and preferably 30 C. to 100 C. A standardequilibration catalyst such as sulfuric acid, a phosphorous halogencompound, as disclosed in Bluestein, Pat. 3,271,359 asigned to the sameassignee as the present invention, etc., can be employed.

In instances where addition between siloxane hydride andimido-substituted aliphatically unsaturated monomer is effected to makeimido-substituted organopolysiloxane, a platinum catalyst such aschloroplatinic acid, can be employed along with a suitable organicsolvent. Other platinum catalysts include Lamoreau, Pat. 3,220,972,Ashby, Pat. 3,159,601, etc. assigned to the same assignee as the presentinvention.

A further method of preparing the imido-substituted organopolysiloxanesof the present invention involves the hydrolysis of imido-substitutedorganosilanes of Formula 6, or the cohydrolysis of such silanes withother organosilanes previously described having hydrolyzable radicalsattached to silicon and monovalent organic radicals, such as monovalenthydrocarbon radicals, halogenated monovalent hydrocarbon radicals andcyanoalkyl radicals.

In addition to the aforementioned aliphatically unsaturated monomers andorganic polymers which can be employed with the imido-substitutedpolysiloxanes, there also can be employed in proportions of 0 to 200parts of fillers, per 100 parts of the imido-substitutedorganopolysiloxane, such as treated clay, ground quartz, fume silica,said, carbon black, glass fibers, glass beads, carbon fiber, boronfiber, quartz fiber, etc. In addition, other ingredients such assolvents at from 60% to by weight of the curable compositions such asN-methyl pyrollidone, dimethylacetamide, toluene, methylene chloride,methylacetate, methylethylketone, plasticizers such as trioctyltrimellitate, diisodecylphthalate, etc. also can be utilized.

In order that those skilled in the art will be able to master theinvention, the following examples are given by way of illustration andnot by way of limitation. All parts are by weight.

EXAMPLE 1 A mixture of 19.6 parts of maleic anhydride and 50 parts ofN,N-dimethylformamide was added to a mixture of 27.6 parts ofbis(6-aminobutyl)tetramethyldisiloxane and parts ofN,N-dimethylformamide. The mixture was stirred at 40 C. for four hoursand then refluxed for six hours. The mixture was then stripped ofsolvent and the residue was dissolved in ether. The ether solution waswashed with a 10% potassium carbonate solution and then further washedwith distilled water. The mixture was then stripped of ether. Theproduct was then dried azeotropically with toluene, and further vacuumstripped of solvent. Based on method of preparation, the product wasbis(5-maleimidobutyl)tetramethyldisiloxane. Its identity was furtherconfirmed by elemental analysis, and its infrared and NMR spectra.

EXAMPLE 2 There are added 27.6 parts ofbis(6-aminobutyl)-tetramethyldisiloxane to a mixture of 30 parts oftetrahydrophthalic anhydride and 100 parts of dry toluene. The mixtureis stirred for 16 hours. There is then added to the mixture, two partsof -toluenesulfonic acid and the resulting mixture is refluxed. When thewater of reaction has been completely removed, the reaction product iswashed with a five percent sodium bicarbonate solution and then driedazeotropically. Based on method of preparation, and its infrared and NMRspectra, the product isbis(fi-tetrahydrophthalimidobutyl)-tetramethyldisiloxane.

7 EXAMPLE 3 There is added 27.6 parts of bis(6-aminobutyl)tetramethyldisiloxane to a mixture of 33 parts ofendomethylene-tetrahydrophthalic anhydride and 100 parts of dry toluene.The mixture is stirred for 16 hours and two parts of pyridine are added.The mixture is then refluxed until the water of reaction is completelyremoved. The product is then stripped under reduced pressure. Based onmethod of preparation, the product isbis(6-endomethylenetetrahydrophthalimidobutyl)-tetramethyldisiloxane.

EXAMPLE 4 A mixture of 44 parts ofbis(6-maleirnidobutyl)tetramethyldisiloxane, 7.4 parts ofctamethylcyclotetrasiloxane, and one part of 95.5 percent sulfuric acidis heated for four hours at 80 C. The mixture is allowed to cool to roomtemperature and grams of water are added. The organopolysiloxane layeris recovered and washed twice with 10 parts of water. The product isthen dried over anhydrous potassium carbonate. Based on the method ofpreparation, the product is a e-maleimidobutyldimethylsiloxychain-stopped polydimethylsiloxane. The identity of the product isfurther confirmed by its infrared spectrum.

EXAMPLE 5 A mixture of parts ofbis(fi-tetrahydrophthalimidobutyl)tetramethyldisiloxane, 7.4 parts ofoctamethylcyclotetrasiloxane and one part of 95.5 percent sulfuric acidis stirred for four hours at a temperature of 80 C. The mixture isallowed to cool and washed three times with 10 parts of water. Theproduct is then dried over potassium carbonate. Based on method ofpreparation, the product is afi-tetrahydrophthalimidobutyldimethylsiloxy chain-stoppedpolydimethylsiloxane. Its identity is further confirmed by its infraredspectrum.

EXAMPLE 6 A mixture of 27.6 parts ofbis('y-aminopropyl)tetramethyldisiloxane, 7.4 parts ofoctamethylcyclotetrasiloxane, and one part of potassium hydroxide isstirred for four hours at 80 C. The mixture is allowed to cool to roomtemperature. The mixture is then neutralized with a standardhydrochloric acid solution. The mixture is then washed several timeswith water and dried over anhydrous potassium carbonate. Based on methodof preparation, the product is a 'y-aminopropyldimethylsiloxy terminatedpolydimethylsiloxane.

There is added to parts of the above 'y-aminopropyldimethylsiloxyterminated polydimethylsiloxane, 33 parts of endomethylenetetrahydrophthalic anhydride in 100 parts of toluene. To the resultingmixture, there is added .01 part of pyridine. The resulting mixture isrefluxed until the water of reaction is azeotroped. The mixture is thenstripped of toluene. Based on method of preparation, the product is a'y-endomethylenetetrahydrophthalimidodimethylsiloxy terminatedpolydimethylsiloxane. Its identity is further confirmed by its infraredspectrum.

EXAMPLE 7 An equal molar solution in hexane of maleic anhydride and'y-aminopropyltriethoxysilane containing about .1 percent by weight ofpyridine was refluxed until all of the water of reaction was separated.The mixture was then stripped of solvent. There was obtained a softwhite solid. Based on method of preparation, the product was'y-maleimidopropyltriethoxysilane. Its identity was further confirmed byelemental analysis and its infrared spectrum.

10 grams of the above silane are added to 100 grams of a one percentsulfuric acid solution. The mixture is heated for 30 minutes at atemperature of about 80 C. The product is recovered by decanting thewater from the mixture. Based on method of preparation, the product isan organopolysiloxane consisting essentially of chemically-combined'y-maleimidopropylsiloxy units. The product is dissolved in toluene anda film is cast from the resulting solution. The film is found to exhibitvaluable insulating characteristics.

EXAMPLE 8 There are added 33 parts of endomethylenetetrahydrophthalicanhydride to a mixture of 30 parts ofv-aminopropylmethyldimethoxysilane, 150 parts of anhydrous toluene, andtwo parts of pyridine. An exothermic reaction occurs immediately. Themixture is refluxed until all of the water formed during the reaction isremoved. The mixture is then stripped of toluene under reduced pressure.Based on method of preparation, the product is 'yendomethylenetetrahydrophthalimidepropylmethyldimethoxydisilane. Itsidentity is further confirmed by its infrared spectrum.

A mixture of 100 parts of a silanol terminated polydimethylsiloxanehaving an average of about 18 chemically-combined dimethylsiloxy units,10 parts of the above silane, and 0.1 part of stannous octoate is heatedat C. for about 10 hours. The viscosity of the mixture graduallyincreases. A product is obtained having a significantly higher molecularweight than the aforementioned silanol-terminated polydimethylsiloxane.Based on method of preparation, the product is a high molecular Weightsilanol terminated polydimethylsiloxane consisting essentially ofchemically-combined blocks of polydimethylsiloxane joined together by-endomethylenetetrahydrophthalimidopropylsiloxy units.

EXAMPLE 9 Several blends were prepared of bis(5-maleimidobutyl)tetramethyldisiloxane and various organic polymers. The blends weremilled at a temperature between C. to 140 C., and consisted of 20 partsof the imido substituted disiloxane, 80 parts of organic polymer, andtwo parts of dicumylperoxide. The blends were then molded for 30 minutesat 150 C. Test slabs were measured for T, tensile (p.s.i.) and E,elongation (percent), at 25 C. and C. Corona resistance CR, is thefactor obtained by dividing the breakdown time, at 1,200 volts and 3,160hertz of the test slab, as compared to the breakdown time of apolyethyleneterephthalate film of equivalent thickness. The resultsobtained are shown as follows:

Various blends were made of bis(6-maleimidobutyl)- tetramethyldisiloxaneand several aliphatically unsaturated organic monomers. The blendsconsisted of 20% by weight of the disiloxane and 80% by weight of theorganic monomer, which included styrene, diallyl phthalate, andN-phenylmaleimide. Solutions of the blends were made which contained 66%by weight of organic solvent. The styrene and diallyl phthalate blendswere dissolved in N- methylpyrollidine and the N-phenylmaleimide blendwas dissolved in ethylenedichloride. There was also added to each of theblends about 0.3% by weight of benzoylperoxide.

The solution blends, as described above, were poured onto aluminumsubstrates. They were cured at 80 C. for 30 minutes and then for anadditional 30 minutes at C. and for 60 minutes at 200 C. All of theblends produced strong self-supporting films that were flexible andinsoluble in methylene chloride. The films made from styrene anddiallylphthalate remained self-supporting at temperatures of up to 250C. All of the films were found to be valuable insulating materials.

Although the above examples illustrated only a limited number of themany imido-substituted organopolysiloxanes provided by the presentinvention, as well as curable blends of these materials and methods formaking them, it should be understood that the present invention isdirected to a much broader class of materials and methods for makingthem as shown by the description preceding these examples.

We claim:

1. A curable organopolysiloxane composition comprising animido-substituted organopolysiloxane and an organic polymer, where theimido-substituted organopolysiloxane has the formula,

(M) .sio (Fkb) 2 and is present in the curable organopolysiloxanecomposition at a proportion of at least 15 percent by weight and theorganic polymer is a member selected from the class consisting ofpolyvinylchloride, polyethylene, polypropylene, polycarbonates,polysulfones, polystyrene, polyurethane, polyesters,polyphenyleneoxides, acrylonitrilebutadiene-styrene terpolymers, andpropylene-ethylene copolymers, M is an imido organo radical of theformula,

0 wherein R is an aliphatically unsaturated divalent organic radical,selected from the class consisting of hydrocarbon radicals andhalogenated hydrocarbon radicals, R is a divalent organo radicalselected from the class consisting of hydrocarbon radicals andhalogenated hydrocarbon radicals, R is selected from monovalenthydrocarbon radicals, halogenated monovalent hydrocarbon radicals andcyanoalkyl radicals, a has a value equal to .002 to 3 inclusive, and bhas a value of 0 to 2.5 inclusive, and the sum of a-l-b has a value of 1to 3 inclusive.

2. A curable organopolysiloxane composition in accordance with claim 1,where the organic polymer is polyethylene.

3. A curable organopolysiloxane composition in accordance with claim 1,where the organic polymer is polyvinylchloride.

4. A curable organopolysiloxane composition in accordance with claim 1,where the aliphatically unsaturated organic polymer isethylene-propylene 1,4-hexadiene terpolymer.

5. A curable organopolysiloxane composition in accordance with claim 1,where the organic polymer is poly (acrylonitrile-butadiene-styrene) 6. Acurable organopolysiloxane composition comprising an imido-substitutedorganopolysiloxane and an ali- 10 phatically unsaturated organic monomerwhere the imidosubstituted organopolysiloxane has the formula,

(M) aSiO and is present in the curable organopolysiloxane composition ata proportion of at least 15 percent by weight, and the aliphaticallyunsaturated organic monomer is selected from the class consisting ofstyrene, m-phenylene bismaleimide, N-phenylmaleimide, diallylphthalate,vinyl chloride, isobutylene, butadiene, isoprene,chlorotrifluoroethylene, Z-methylpentene-l, vinyl formate, vinylacetate, acrylonitrile, vinyl methyl ether, vinyl methyl ketone, estersof acrylic acid, esters of methacrylic acids, divinyl benzene, triallylcitrate, triallyl cyanurate, N-vinylphthalimide, N-allyl phthalimide andN-allyl tetrachlorophthalimide, and M is an imido organo radical of theformula wherein R is an aliphatically unsaturated divalent organicradical, selected from the class consisting of hydrocarbon radicals andhalogenated hydrocarbon radicals, R is a divalent organo radicalselected from the class consisting of hydrocarbon radicals andhalogenated hydrocarbon radicals, R" is selected from monovalenthydrocarbon radicals, halogenated monovalent hydrocarbon radicals andcyanoalkyl radicals, a has a value equal to .002 to 3 inclusive, and bhas a value of 0 to 2.5 inclusive, and the sum of a+b has a value of 1to 3 inclusive.

7. A curable organopolysiloxane composition in accordance with claim 6,comprising the imido-substituted organopolysiloxane and styrene.

8. A curable organopolysiloxane composition in accordance with claim 6,comprising the imido-substituted organopolysiloxane andN-phenylmaleimide.

9. A curable organopolysiloxane composition in accordance with claim 6,comprising the imido-substituted organopolysiloxane anddiallylphthalate.

References Cited UNITED STATES PATENTS SAMUEL H. BLECH, Primary ExaminerUS. Cl. X.R.

